Characterization of a Halotolerant Fungus from a Marine Sponge

Abstract

Introduction Marine sponges have established symbiotic interactions with a large number of microorganisms including fungi. Most of the studies so far have focussed on the characterization of sponge-associated bacteria and archaea with only a few reports on sponge-associated fungi. During the isolation and characterization of bacteria from marine sponges of South Australia, we observed multiple types of fungi. One isolate in particular was selected for further investigation due to its unusually large size and being chromogenic. Here, we report on the investigations on the physical, morphological, chemical, and genotypic properties of this yeast-like fungus. Methods and Materials Sponge samples were collected from South Australian marine environments, and microbes were isolated using different isolation media under various incubation conditions. Microbial isolates were identified on the basis of morphology, staining characteristics, and their 16S rRNA or ITS/28S rRNA gene sequences. Results Twelve types of yeast and fungal isolates were detected together with other bacteria and one of these fungi measured up to 35 μm in diameter with a unique chromogen compared to other fungi. Depending on the medium type, this unique fungal isolate appeared as yeast-like fungi with different morphological forms. The isolate can ferment and assimilate nearly all of the tested carbohydrates. Furthermore, it tolerated a high concentration of salt (up to 25%) and a range of pH and temperature. ITS and 28S rRNA gene sequencing revealed a sequence similarity of 93% and 98%, respectively, with the closest genera of Eupenidiella, Hortaea, and Stenella. Conclusions On the basis of its peculiar morphology, size, and genetic data, this yeast-like fungus possibly constitutes a new genus and the name Magnuscella marinae, gen nov., sp. nov., is proposed. This study is the first of its kind for the complete characterization of a yeast-like fungus from marine sponges. This novel isolate developed a symbiotic interaction with living hosts, which was not observed with other reported closest genera (they exist in a saprophytic relationship). The observed unique size and morphology may favour this new isolate to establish symbiotic interactions with living hosts.

Genomic characterization of three marine fungi, including Emericellopsis atlantica sp. nov. with signatures of a generalist lifestyle and marine biomass degradation

“…The ability to process any source of nutrients efficiently would be beneficial in a nutrient poor ocean environment (Turley 2000 ). Sponges are natural filters for organic matter such as marine snow and naturally concentrate the availability of different nutrients, therefore fungi may exploit this by living within the sponge and adapt specifically to that environment (Anteneh et al 2019 ).…”

Physiological aspects of the halophilic and halotolerant fungi, and their potential applications

“…Isolation of the halophilic fungi from the microbial communities of high salt contents is challenging, and mainly depends on the enrichment followed by cultivation using different nutritional parameters (Anteneh et al, 2019). Diversities among the halophilic or the halotolerant fungi depend on their habitats and physiological requirements.…”

Cultivation and diversity analysis of novel marine thraustochytrids

“…Generally, multiple media arrangements are advantageous to investigate the culturable diversity. Referring to an experiment with several kinds of culture media, novel yeast-like fungi were harvested only using soluble starch-yeast extract-peptone agar medium; yeasts were obtained only from soluble starchyeast extract-peptone agar medium, asparagine-peptone agar medium and marine agar medium (Anteneh et al 2019). To understand the diversity in specific habitats, six media were used to isolate fungi from Gorgonians and soft corals (Zhang et al 2012(Zhang et al , 2019b.…”

“…To understand the diversity in specific habitats, six media were used to isolate fungi from Gorgonians and soft corals (Zhang et al 2012(Zhang et al , 2019b. In the isolation experiments with three sponge samples, new strains were observed only in one sample (Anteneh et al 2019), suggesting the importance of sampling repetition.…”

“…In addition, the cultivation temperature and antibiotics used in the above mentioned work were similar to that of most thraustochytrid strains. Clearly, it is possible to apply isolation strategies and techniques of (Anteneh et al 2019) marine fungi and bacteria to be adapted to isolate thraustochytrids in the future. For example, to obtain new species of thraustochytrids, the repetition of sampling, the source of isolation materials, inoculation with multiple media, and culture at a temperature as close to its natural environment as possible are noteworthy.…”